Wuzaa! and here is a bomb for you to look at hehe...
1. Power up or what ever that "P-logo" is just don't look good
2. Same thing with the lifebar(hearts), also white outlines don't just fit the style i'd remove them : P
3. Bg only needs a bit more rendering with those white/red clouds :/ if you want to keep it pretty simple.
4. Rock tiles well you got that already in your remake list eh? hehe
5. Player ship, yea it is something you maybe don't want to stuck with but i'd trash it and make a new one with simpler design and definitely with umm... a fresh color like blue. Coloring is pretty much same with the enemies currently so yeah i'd add a heroic color into it!
I'll make an edit if you don't get it... rimmed well eh?
but yeah that's pretty much all i have to give now